1. Field of the Invention
The invention relates generally to imaging target components in a biological sample. More specifically, methods and apparatus are described that provide for the positive selection of target cells in a blood sample. Small permanent magnets are added directly to a blood sample containing CD4 immuno-magnetic labeled fluorescently stained AO whole blood.
2. Background Art
The use of immunomagnetic separation technology provides greater sensitivity and specificity in the detection of target entities in blood for example, but not limited to, intact circulating cancer cells and endothelial cells. This simple and sensitive diagnostic tool, as described (U.S. Pat Nos. 6,365,362; 6,551,843; 6,623,982; 6,620,627; 6,645,731; WO 02/077604; W003/065042; and WO 03/019141, all incorporated by reference) can be used in the present invention to correlate the statistical survivability of an individual patient based on a threshold level.
A prior diagnostic tool incorporates a blood sample from a cancer patient (WO 03/018757) incubated with magnetic beads, coated with antibodies directed against an epithelial cell surface antigen as for example EpCAM. After labeling with anti-EpCAM-coated magnetic nanoparticles, the magnetically labeled cells are then isolated using a magnetic separator. The immunomagnetically enriched fraction is further processed for downstream immunocytochemical analysis or image cytometry, for example, in the CELLSPOTTER® System (Immunicon Corp., PA), a fluorescent cell imaging system. The magnetic fraction can also be used for downstream immunocytochemical analysis, RT-PCR, PCR, FISH, flowcytometry, or other types of image cytometry.
The CELLSPOTTER® System (Immunicon Corp., PA), a fluorescent cell imaging system, utilizes immunomagnetic selection and separation to highly enrich and concentrate any epithelial cells present in whole blood samples. The captured cells are detectably labeled with a leukocyte specific marker and with one or more tumor cell specific fluorescent monoclonal antibodies to allow identification and enumeration of the captured CTC's as well as unequivocal instrumental or visual differentiation from contaminating non-target cells. At an extraordinary sensitivity of 1 or 2 epithelial cells per 7.5-30 ml of blood, this assay allows tumor cell detection even in the early stages of low tumor mass.
EASYCOUNT™ system (PCT/US03/04468) is a fluorescent imaging system, designed to make a distinction between lymphocytes, granulocytes and monocytes. The system includes a compact electronic optical instruments, analytical methods, image acquisition, and data reduction algorithms for the detection and enumeration of magnetically labeled target cells or particles. Using whole blood as an example, blood cells are fluorescently labeled using one or more target specific fluorescent dyes, such as a DNA staining dye. The cells of interest or target cells in the blood sample are labeled by incubation with monoclonal antibodies conjugated to ferromagnetic particles. The sample is then placed into an appropriate optical detection chamber or covet, which in turn is placed into a magnetic field gradient that selectively causes the magnetically labeled cells to move towards the planar viewing surface of the chamber. The target cells are collected and immobilized substantially uniformly on the optically transparent surface of the chamber. A segment of this surface and the labeled target cells thereon are illuminated by means of one or more LED (light emitting diodes). Subsequently, the light emitted by individual target cells is captured by a CCD (charge coupled device). Image acquisition methods, processing methods, and algorithms, disclosed herein, are used to count the number of captured light-emitting cells and to relate the data output to the target cells per microliter of the analysis sample in the chamber and ultimately to the original specimen.
Currently available methods do not provide a rapid, low cost and consistently reliable means for assessing a target population of cells by flow or image cytometry. Thus, there is a clear need for quick and accurate detection of target components in blood such as cancer or endothelial cells.